1. Field of the Invention
The present invention relates to a device and method for managing power in a computer system.
2. Background of the Related Art
In a general computer system such as a notebook computer or a desktop computer, according to a system operating state, an operating system adjusts the power management state of a CPU to one of the states C0 to C4 defined in the ACPI (Advanced Configuration and Power Interface) standard, as shown in FIG. 1. The C0 state is a CPU working state, the C1 state is a CPU halt state and the C2 state is a CPU sleep state with a clock input being granted. The C3 state is a CPU stop state with an external clock input being stopped, and the C4 state is a C3 state with a low drive voltage being applied. In general, if the CPU enters an idle state, the power management state becomes the C3 or C4 state defined in the ACPI standard to prevent unnecessary power consumption.
When the operating system executes only a program for an audio device through an interface with an audio controller or only a program for a USB device through an interface with a USB controller, the CPU of the computer system is operated at only about 10% of the maximum performance mode. Although when the operating system executes only the audio device program or the USB device program and the CPU of the computer system operates at only about 10% of the maximum performance mode, the CPU maintains the C2 state (i.e., a CPU sleep state with a clock input being granted) unchanged or C1 state, causing unnecessary power consumption.
As described above, the related art computer system has various disadvantages. For example, in a notebook computer, unnecessary maintenance of the C2 state leads to unnecessary power consumption of about 1.5 W since the power consumption difference between the states C2 and C3 is 1.5 W, which also causes an increase in the system temperature due to the CPU's heat.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.